1. Field of the Invention
The present invention relates to a disk drive device that drives a recording disk.
2. Description of the Related Art
Recently, disk drive devices such as HDDs (Hard Disk Drives) are required to be further small in size. With such background, in a disk drive device that record data, for example, magnetically, data are recorded/reproduced with a magnetic head flying above a recording disk such that a slight gap between both is maintained while the recording disk is being rotated at a high speed. In order to miniaturize such a disk drive device, there is a demand that data are recorded/reproduced with the gap between the magnetic head and the recording disk being extremely narrow, for example, less than or equal to 10 nm.
In order to miniaturize disk drive devices, a magnetoresistive effect element (hereinafter, referred to as an “MR element”) is used for the magnetic head. Due to the use of the MR element in such a narrow gap, there is a fear that a thermal asperity failure (hereinafter, referred to as “TA failure”) or a head crash failure may occur in the magnetic head. Specifically, the TA failure means that: minor foreign substances on the surface of the recording disk are in contact with the MR element while the magnetic head is flying to trace the recording tracks, and therefore heat is momentarily caused in the MR element due to kinetic energy of the foreign substances; and the resistance value of the MR element momentarily varies with the MR element being momentary heated followed by being cooled, resulting in superimposition of the varied resistance value on a reproduced signal as a noise such that correct reading of the reproduced signal is interfered.
For example, Japanese Patent Application Publication No. Hei 11-120533 discloses a disk drive device in which a groove is provided near the record/reproduction element of the magnetic head in order to collect minor dust or foreign substances in the groove.
As a result of an investigation by the present inventor, the flowing knowledge has been acquired that the TA failure is caused with foreign substances (hereinafter, referred to as “particles”) that adhere to a disk drive device, having a size of 0.1 μm to approximately several μm, adhering to the surface of a recording disk due to a vibration or a flow of air.
The disk drive device is provided with a member that forms a closed clean air space filled with clean air, and further provided with a recording disk and a hub that drives the recording disk mounted thereon in the clean air space, a bearing unit that rotatably supports the hub, a spindle drive unit that rotatably drives the hub, and a drive unit that drives the magnetic head in a fluctuating manner.
Particles sometimes occur from the member that forms the clean air space. The particles enter the clean air space and adhere to the recording disk. As more particles adhere to the recording disk, the probability of an occurrence of TA failure is increased. In addition, if more particles exist in the clean air space when the gap between the magnetic head and the recording disk is narrower, the probability of an occurrence of TA failure is increased. Thereby, correct reading of a reproduced signal may be interfered.